June 11, 1968 G. ATMAN 3,388,027 GRAPHIC MATERIALS IN CORPORATING MICROSPHERE DISTRIBUTIONS FOR THE PRESENTATION OF VISUAL INFORMATIO Filed March 2, 1966

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Aé7/ears of 24ss aw/crosa Aeres s2 u/c 2/7/a A- 2a2ae wasézysza7ary 224 SS152 feared a reasiered eyvans 1766 E2E2EE Aé f/ec 7.9 ave 72/ s/Ma 7aley 2 aeer sta or7 3,388,027 United States Patent Office Patented June 1, 1968 2 Brief description of drawing 3,388,027 For a fuller understanding of the nature and objects GRAPEC MATERALS ANCORPORATENG MICRO SPEERE OFSTREBUTIONS FOR THE PRESENTA of the present invention, reference should be had to TON OF WSUAL INFORMATION the following detailed description, taken in connection Gerald Altaan, 4 Westminster Road, with the accompanying drawings, wherein: Newton Center, Mass, 02159 FIG. 1 is an exaggerated cross sectional view of an over. Continuation-in-part of application Ser. No. 249,35, head projection product embodying the present inven Jan. 4, 1963. This application Mar. 2, 1966, Ser. tion; - - No. 532,298 FIG. 2 is an exaggerated cross sectional view of a 8 Claims. (C. 61-4) O photographically developed product embodying the present invention; FIG. 3 is an exaggerated cross sectional view of a ASTRACT OF THE DESCLOSURE multicolor printed product embodying the present inven Visual products for the display of images are provided tion; with strata of microspheres of selected optically operative 5 FIG. 4 is an exaggerated cross sectional view of a trans characteristics. The distribution of the microspheres, by lucent projection product embodying the present inven virtue of their small size, area concentration, refractive tion; and index and optically clear bond to their support, operates FIG. 5 is an exaggerated cross sectional view of a to control diffused and concentrated light for projection projection scribing product embodying the present inven 20 tion. and observation. Detailed description Generally, the products illustrated herein utilize glass Background and summary of the invention microspheres of optical clarity, of which 90% by weight The present invention relates to graphic materials that 2 5 range in diameter from 30 to 1 micron or below, and both are to be viewed by direct observation and are to be which have an index of refraction that ranges in various imaged by projection. More particularly the present in applications from 1.5 to 2.6. Especially suitable glass vention relates to graphic sheets of a type that is char microspheres of the foregoing type are soid by Cataphote acterized by a distribution of minute refracting optical Corporation, Jackson, Miss., under the trade designation spheres, which preserve pleasing diffusion of light trans 30 No. 4000 Extra Fine Uni-Spheres, a product composed mitted from the sheet directly to the eye but which en of high-grade optical crown glass, soda-lime type, with sure efficient utilization of light projected from the sheet silica content not less than 60%, and having an N rang to a viewing screen or the like. ing from 1.5 to 1.9. Also suitable are glass microspheres The present application is a continuation-in-part of of like Small diameter having analagous compositions ex U.S. patent application No. 249,351, filed Jan. 4, 1963, now 3. 5 cept for the addition of optimum high concentrations of Patent No. 3,269,839, issued Aug. 30, 1966, in the name lead or titanium, and having an ND ranging from 1.9 to of the applicant hereof for Optical Products, Processes 2.6. These microspheres are adhered to the illustrated and Devices. The disclosure of this patent, which is in substrates by an optically clear polymer, for example, corporated into the present disclosure by reference, illus gelatine, which has been applied from a suitable polar trate uses for which materials of the present invention 40 solvent such as water, inseed oil which has been applied are intended. from a suitable organic solvent such as turpentine or A primary object of the present invention is to provide methyl methacrylate which has been applied from a selected graphic materials of the foregoing type, by which suitable organic solvent such as toluene. The area con directly viewed diffuse light may be effectively produced centration of the microspheres is maximized to achieve a by any randomly selected source but by which projected 45 covering power preferably of at least 90%, there being concentrated light may be effectively utilized for image a range of larger microspheres which are virtually in formation at a distance. In such applications as printing contact with each other, i.e., no more than 10% of with ink, photography with developable particles, etc., it is their average diameter apart, a range of smaller micro advantageous to select the optical constants of the re spheres which cover the interstices defined by three or fracting spheres, particularly diameter and index of re 50 more adjacent larger microspheres, and in some cases fraction, for optimum observation vs. projection relation additional layers of larger or smaller microspheres to ships. In such applications, it is important that the re cover interstices in other layers. The substrate to which fracting sphere distribution macroscopically provide a fiux the microspheres are applied is a continuous thin layer, cross section that in effect is an optical continuum. preferably at most 0.001 inch, of a high (i.e. at least Other objects of the present invention are: to coat 55 90%) reflectance metal, such as aluminum or silver, the surface of aluminum foil, via an optically clear ce which has been deposited on or laminated to a suitably ment, with particularly selected minute glass spheres that thick (e.g. 0.0005 to 0.05) paper such as baryta or poly adjacently contact each other in order to provide a reflux mer such as cellulose acetate or cellulose nitrate. The reflecting graphic sheet; to relate the optical constants of overall selection of materials is such that a very large such minute glass spheres to the visual subject matter of 60 proportion of directive incident light is returned toward strata in contact therewith and predeterminedly spaced its source with controlled dispersion. The minimization of therefrom; to print with colored minute glass spheres of dispersion in the reflex reflected light cone, which is char the foregoing type; to enhance the projection capabilities acteristic of traffic control reflex reflective materials well of a translucency; and to provide a simple scribing tech known in the prior art, is not a primary consideration in nique that is adapted for direct diffuse observation and 65 the cross of the present materials because the present projection image production. materials are to be used in an optical system that inter Other objects of the present invention will in part be cepts the major proportion of the integrated flux cross obvious and will in part appear hereinafter. section of a reflex reflected light cone that is broader The invention accordingly comprises the products and than that needed by the prior materials. In order to relationships among their components, which are exempli 70 achieve proper index of refraction relationships between fied in the following detailed disclosure, the scope of the glass microsphere stratum and other strata of the which will be indicated in the appended claims. product of the present invention, the glass microsphere 3,388,027 3 4. stratum, in various forms, inciudes two or more Sub 48 are analagous to the counterparts in FIGS. 1, 2 and 3. strata of glass microspheres of different ND or includes Normally opaque layer 44 is composed of a polar acting glass microspheres of different ND in predeterminedly dye which clears in acid or alkali, for example, pheno interspersed relation. An important feature of the present phthaline dispersed in a gelatine matrix. On the surface of materials is that the natural diffraction and aberration opaque stratum 44 are shown in dried microsphere "ink' of the glass microspheres ensure sufficient scattering of originally containing a dispersion of microspheres, of randomly incident light to produce a white (or predeter either high or low index of refraction, in an aqueous minedly colored) appearance when viewed normally. The alkaline gelatine solution. When this ink is "written' onto following examples of materials of the present invention opaque stratum 44, alkaline clearing takes place as at are in reference to the figures of the drawing. 0 5 and the glass microspheres are retained in position FIGURE 1 shows "open faced' layer of glass micro as at 52 to provide localized reflex reflecting regions spheres 0 bonded to a reflective metal coil 12 which is having desired alphanumeric or symbolic configurations. jaminated to a paper support 4. Microspheres 10 range The present thus provides a variety of products that in diameter from 1 to 30 microns and have an index of may be viewed comfortably in terms of diffuse light and refraction, N=1.9. The outer hemispheres of micro 5 may be projected effectively in terms of concentrated spheres it are free of adhesive and the inner hemi light. Since certain changes may be made in the above spheres are bonded to foil 2 by a clear epoxy adhesive disclosure without departing from the scope of the in stratum having a depth of molecular dimension. Foil 12 vention herein involved, it is intended that all matter in turn is bonded by a similar adhesive to paper support contained in the foregoing description or illustrated in 14, which for example is composed of suitable kraft 20 the accompanying drawing be interpreted in an illustra sheeting. The arangement is such that in excess of 90% of tive and not in a limiting sense. the area of foil 12 is covered by microspheres and the What is claimed is: uncoated interstices serve as light conduits also by virtue 1. A graphic product for direct observation in terms of the reflectivity of the side surfaces of the microspheres of diffuse light and for image projection in terms of con that bound the interstices. The product of FIG. 1 is suit 25 centrated light, said graphic product comprising, in lami able for direct marking for use in an episcopic projector. nated Sequence, a paper-like backing stratum, a continu In a modification of the product of FIG. 1, a photo ous metal reflecting stratum and a glass microsphere graphic transparency or other graphic representation is stratum, said microsphere stratum being composed of a interposed at 6 between microsphere layer 10 and foil multiplicity of microspheres which cover at least 90% 12. In various forms, the photographic transparency is a 30 of any selected macroscopic area of said metal reflecting sveloped silver halide, diazo, ferric, photopolymeric or stratum, at least 90% of said microspheres being less photothermographic print. This representation is suitable than 30 microns in diameter, said multiplicity including a for both direct observation and episcopic projection. range of larger microspheres defining interstices there FIG. 2 illustrates, in laminated sequence, a photographic among and a range of Smaller microspheres filling said print stratum 58, an optical spacing stratum 20, a glass interstices, adjacent microspheres of said multiplicity microsphere stratum 22, a reflecting metal stratum 24 and being substantially in contact with each other, the bond a paper support stratum 26. Photographic print stratum between said multiplicity of microspheres and said metal 18 is a gelatino silver print. Spacing stratum is composed reflecting stratum being optically clear in order not to of gelatine and is sufficiently thick, e.g. .05 inch, to pre obstruct access of light through said microsphere stratum determinedly defocus glass microsphere stratum 22 when 40 to said metal reflecting stratum, substantially all of said photographic print stratum 18 is in focus in an episcopic multiplicity of microspheres being characterized by an projector. The glass spheres are of titanium or lead glass oLiter optical surface remote from said metal reflecting having an N ranging from 1.9 to 2.6. This high ND differs Stratum and an inner optical surface contiguous with from the ND of outer gelatine strata sufficiently to en Said metal reflecting stratum, said outer optical surface sure predetermined refraction. being free to receive and transmit light incident on said FIG. 3 illustrates, in laminated sequence, a three color microsphere stratum, said multiplicity of microspheres halftone printed stratum 28, a reflecting aluminum stratum by virtue of their specified size, area concentration and 38 and a paper support 32. This product is formed by optically clear bond to said metal reflecting stratum an ordinary multicolor printing press having rollers which operating to diffuse randomly incident light for direct first apply metal layer 30 (either as foil as flake in a 50 viewing and to concentrate directed light for episcopic binder) to paper stratum 32 and then apply successive projection. halftone coats of cyan ink 34, magenta ink 36 and yellow 2. The product of claim 1 wherein a developed photo ink 38. As shown each of these inks includes crystal clear graphic stratum is laminated to the outer face of said glass microspheres in a dyed matrix, the latter being microSphere stratum. composed of conventional viscous linseed varnish contain 3. The graphic product of claim 2 wherein said photo ing an appropriate chromophoric dye. In an alternative graphic stratum contains silver. form of the product of FIG. 3, the glass spheres are 4. The graphic product of claim wherein a visual colored and the varnish is clear. This form of the inven presentation stratum is interposed between said micro tion contemplates a two color process in which the only Sphere stratum and said reflecting stratum. glass spheres are generally red and generally white appro 60 5. The graphic product of claim 1 wherein said micro priately representing color separation scenes that are gen spheres are associated in different regions and character erally blue and generally red. ized by different colors. FIG. 4 illustrates a clear plastic sheet 40 composed 6. The graphic product of claim 5, wherein a generally of gelatin or other flow index of refraction material, on opaque masking stratum is interposed between said re which is disposed a distribution of microspheres 42 com 65 flecting stratum and said microsphere stratum, said micro posed of glass having a relatively high index of refrac sphere stratum having restricted and separated concen tion, preferably ranging from 1.8 to 2.6. Adhesion be trations of microspheres, said masking stratum being tween the glass microspheres and the plastic sheet is ef cleared in the vicinity of concentrations. fected by an aqueous mixture of 50%-50% gelatire and 7. A product comprising an optically clear support glycerine. This product is useful as a Support for a photo 70 sheet, a glass microsphere stratum carried thereby, and graphic representation to be projected diascopically or a bonding material joining said microsphere stratum to as a rear projection screen. said support sheet, said microsphere stratum being com FIG. 5 illustrates a normally opaque layer 44 that posed of a multiplicity of microspheres which cover at may be easily cleared when desired, a metal layer 46 least 90% of any selected macroscopic area of said sup and a paper support 48. Metal layer 45 and paper support port sheet, said bonding material being optically clear, 3,388,027 5 6 at least 90% of said microspheres being less than 30 References Cited microns in diameter, the index of refraction of said micro- UNITED STATES PATENTS spheres being substantially higher than the index of refraction of said support sheet, said multiplicity of 2,354,049 7/1944 Palmquist ------117-35 X microspheres by virtue of their small size, area concen- 5 2,403,752 7/1946 Philippi ------41-33 tration, index of refraction and optically clear bond to 33.33. 1343. FMusicial------li said support sheet operating to substantially diffuse ran 2,997,403 8/1961 Searight ------... 106-193 domly incident light for direct viewing but to substan tially8. Thetransmit graphic concentrated product of light claim for 1 whereinprojection. the index lo NORMAN G. TORCHIN, Primary Examiner. of refraction of said microspheres is at least ND=1.9. R. H. SMITH, Assistant Examiner.